Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON):

Solution:
h, w = map(int, raw_input().split())
grid = [raw_input() for y in range(h)]
dist = [[-1]*w for y in range(h)]
que = [(0,0)]
dist[0][0] = 0
while que != []:
    cx, cy = que.pop(0)
    for dx, dy in [(1,0), (0,1), (-1,0), (0,-1)]:
        nx, ny = cx+dx, cy+dy
        if (0 <= nx < w) and (0 <= ny < h) and (grid[ny][nx] == '.') and (dist[ny][nx] == -1):
            que.append((nx, ny))
            dist[ny][nx] = dist[cy][cx] + 1
d = dist[h-1][w-1]
if d == -1:
    print -1
else:
    print (h*w - d - 1 - sum([len(filter(lambda c: c=="#", line)) for line in grid]))